1. Field of the Invention
The present invention relates to a plasma processing apparatus, such as a sputtering apparatus for forming a thin film of a target material on a substrate in a vacuum chamber.
2. Description of Prior Art
Conventional sputtering apparatuses have, for example, the following configuration: a target and a substrate are arranged in opposition to each other, a gas for generating a plasma between the two is introduced, a plasma is generated by applying a high frequency or a DC voltage in the cathode portion on which the target is arranged, and ions that are accelerated by the magnetic field collide with the target, so that material is knocked out of the target and deposited on the substrate.
FIG. 3 shows the general configuration of such a sputtering apparatus. In FIG. 3, numeral 21 denotes a vacuum chamber, and numeral 22 denotes a cathode portion. A power source 23 is connected to the cathode portion 22. A target 24 of the material to be vapor-deposited is arranged on the cathode portion 22, and a substrate 25 is arranged in opposition to the target 24. Numeral 26 denotes a gas inlet portion, and numeral 27 denotes an exhaust port. The substrate 25 is attached to a holder 28, which can be rotated with a motor 29. Moreover, cooling water can be introduced to the holder 28 from a cooling water inlet unit 30 and the substrate 25 can be cooled with this cooling water.
With this configuration, a plasma-generating gas, such as argon gas, is introduced from the gas inlet portion 26 into the vacuum chamber 21, and exhausted from the exhaust port 27, so as to attain a predetermined sputtering pressure.
Under a predetermined gas pressure in the vacuum chamber 21, a high frequency or a DC voltage is applied to the cathode portion 22 with the power source 23, thereby generating a plasma between the substrate 25 and the target 24. Argon ions in the plasma are accelerated by the magnetic field and collide with the target 24, so that target material is knocked out and flies off into the vacuum. The target material is thus deposited on the substrate 25, whereby a thin film forms thereon. The holder 28, on which the substrate 25 is held, is rotated by the motor 29 and is cooled by introducing cooling water from a cooling water inlet unit 30.
The substrate 25 needs to be cooled constantly because its temperature rises as the substrate 25 is exposed to the plasma generated between the target 24 and the substrate 25 in proximity to each other during the sputtering. At the same time the substrate 25 needs to be rotated, so as to improve the uniformity of the thin film distribution on the substrate 25.
However, in such a conventional sputtering apparatus as described above, the holder 28 has to be provided with a motor 29 and a cooling water inlet unit 30 to rotate the substrate while cooling it. Therefore, there is the problem that a plurality of mechanical units and the space for installing the same are necessary, which poses a limit to making the sputtering apparatus smaller and simpler.